CN113484359A

CN113484359A - Interface material low-temperature thermal resistance measuring device

Info

Publication number: CN113484359A
Application number: CN202110674850.XA
Authority: CN
Inventors: 莫德锋; 张阳; 范崔; 徐红艳; 曾智江; 李雪
Original assignee: Shanghai Institute of Technical Physics of CAS
Current assignee: Shanghai Institute of Technical Physics of CAS
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2021-10-08

Abstract

The invention discloses a device for measuring low-temperature thermal resistance of an interface material. Two or more groups of measuring units are arranged on the upper surface of the cold substrate in a circumferential array around the center of the cold substrate, each group of measuring units and the cold substrate form a one-dimensional heat conduction channel, the thermal resistance of the interface material of the measuring units is measured by a steady state method, the thermal resistance of a plurality of groups of interface materials can be measured by the whole device, the measuring error can be reduced by a contrast method, and the measuring precision is improved. The device has the advantages of simple structure, high precision, short test time, expandable measurement temperature zone to extremely low temperature, high reliability and the like.

Description

Interface material low-temperature thermal resistance measuring device

Technical Field

The invention belongs to the field of heat transfer tests, and particularly relates to a device for measuring low-temperature thermal resistance of an interface material.

Background

The thermal resistance is resistance encountered by heat on a heat flow path, reflects the size of a medium or heat transfer capacity between the media, is a very important thermophysical parameter, has important research value and significance in the aspects of thermal management in multiple engineering fields, including electronic packaging, optoelectronic devices, aerospace technology, metal processing industry, low-temperature engineering and the like, and influences the reliability, performance, power consumption and service life of products to a great extent. Sheet interface materials are often used between two solid mounting surfaces to reduce the interface thermal resistance. The method has important significance in the thermal design link in the engineering application field, and can improve the thermal simulation accuracy and the rationality of thermal design.

Disclosure of Invention

The invention aims to solve the problems that the low-temperature thermal resistance measuring device for the interface material is provided, the defects of the prior art are overcome, the thermal resistance value of the sheet interface material applied in engineering can be rapidly and accurately measured, and the problems that the thermal resistance value of a low-temperature region is difficult to measure, the measuring time is too long, the accuracy of measuring the thermal resistance value is not high and the like in the thermal resistance testing process of the sheet interface material are solved.

A measuring device for low-temperature thermal resistance of an interface material comprises a measuring unit 1, a cold substrate 2, a cooling cold finger 3, a cold substrate temperature measuring element 4, a vacuum cavity 5, a connecting screw 6 and a cavity bottom plate 7. The measuring unit 1 comprises a radiation cover 1.1, a uniform heat block temperature measuring element 1.2, a heating resistance module 1.3, a fixing screw 1.4 and a uniform heat block 1.5. Two or more than two measuring units 1 are arranged on the upper surface of the cold substrate 2 in a circumferential array around the center of the cold substrate 2, fixing screws 1.4 penetrate through mounting through holes on the uniform heating block (1.5) and mounting through holes on the cold substrate 2 and are fixed in mounting threaded holes on the upper surface of the cooling cold finger 3, a radiation cover 1.1 is fixed on the upper surface of the uniform heating block 1.5 through screw connection, the outer surface of the radiation cover 1.1 is polished or plated with a high-reflectivity coating to reduce the surface emissivity, and the size and shape of the radiation cover 1.1 are matched with the size and shape of the uniform heating block 1.5. The heating resistance module 1.3 is connected to the middle position of the upper surface of the uniform heating block 1.5 through glue, the uniform heating block temperature measuring element 1.2 is connected to the position, close to the heating resistance module 1.3, of the upper surface of the uniform heating block 1.5 through glue, the uniform heating block 1.5 is connected and installed above the cold substrate 2 through a fixing screw 1.4, the interface material to be measured is clamped and installed between the uniform heating block 1.5 and the cold substrate 2, the torsion of the fixing screw for fixing the uniform heating block 4 after the interface material to be measured is installed each time is consistent, the uniform heating block 1.5 is circular or rectangular and slightly larger than the interface material to be measured in size, the material adopts a copper or sapphire material with higher thermal conductivity at low temperature, and a high-reflectivity coating is plated on the surface of the uniform heating block 1.5 to reduce the surface. The measuring units 1 and the cold substrate 2 respectively form parallel one-dimensional heat conducting channels. The low-temperature thermal resistance value of the interface material to be measured in each measurement unit 1 can be measured by a steady-state method. The cold substrate 2 is connected and installed on the upper end face of the cooling cold finger 3 through a connecting screw 6, and indium sheets are installed on two contact interfaces so as to reduce interface thermal resistance. The cold substrate 2 is made of copper or sapphire material with high heat conduction at low temperature, and the cold substrate 2 is cylindrical and is matched with the upper end face of the cooling cold finger 3 in size. The upper part of the cooling cold finger 3 is a solid cylinder, the lower part is a cylindrical cavity with an opening at the bottom, and the outer wall of the bottom end of the cooling cold finger 3 is connected with the bottom of the cavity bottom plate 7 in an airtight mode through welding. The vacuum cavity 5 is a cylindrical cavity with a larger radius, and the inner walls of the vacuum cavity 5 and the cavity bottom plate 7 are polished or plated with a high-reflectivity coating so as to reduce the surface reflectivity.

A low-temperature thermal resistance measuring device for interface materials is characterized in that a vacuum chamber is vacuumized by a vacuum pump until the vacuum degree is 10 in the testing process^-4And (3) pouring liquid nitrogen into the cooling cold finger after Pa is higher than Pa, and transmitting cold energy upwards along the radial direction, and sequentially passing through the cooling cold finger 3, the indium sheet, the cold substrate 2, the uniform heating block 1.5 and the heating resistance module 1.3. The temperature of the thermoblock 1.5 is changed by changing the heating power of the heating resistance module 1.3. The temperature of the upper surface of the uniform heating block 1.5 is measured by a uniform heating block temperature measuring element 1.2, and the temperature of the upper surface of the cold substrate 2 is measured by a cold substrate temperature measuring element 4. And after the temperature is stable, the thermal resistance of each group of interface materials to be tested can be obtained by a steady state method.

The invention has three remarkable characteristics: the two or more than two measuring units are arranged on the upper surface of the cold substrate with uniform temperature in a circumferential array around the center of the cold substrate, each measuring unit and the cold substrate respectively form a parallel one-dimensional heat conduction channel, and the low-temperature thermal resistance of a plurality of interface materials can be measured at the same time in each measurement. Secondly, if the interface material in one group of the measuring units is a standard sample with known thermal resistance, the device can eliminate the error of each test by a comparison method, and accurately measure the thermal resistance value of other thermal interface materials to be measured. The cold substrate used by the device is made of high-heat-conductivity copper or sapphire materials, the temperature of the lower surfaces of all groups of interface materials can be guaranteed to be approximately consistent during measurement each time, the uniform heat block is made of high-heat-conductivity copper or sapphire materials, a high-reflectivity coating is plated on the surface of the uniform heat block, the surface of the radiation cover is polished or plated with the high-reflectivity coating to reduce the surface emissivity, the vacuum cavity is vacuumized to eliminate convection heat exchange, the accuracy of one-dimensional stable heat transfer is guaranteed, and experimental errors are reduced. The device has the advantages of simple overall structure, small volume, low quality and short cooling stabilization time, can greatly reduce the time for measuring the thermal resistance value of the low-temperature interface material, and is suitable for rapidly measuring the low-temperature thermal resistance value of the sheet interface material in the engineering field.

Drawings

FIG. 1 is a device for measuring low-temperature thermal resistance of an interface material.

FIG. 2 is a top view of a distribution of measurement units;

1 measuring unit 1.1 radiation cover 1.2 uniform heat block temperature measuring element 1.3 heating resistance module 1.4 fixing screw 1.5 uniform heat block 2 cold substrate 3 cooling cold finger 4 cold substrate temperature measuring element 5 vacuum cavity 6 connecting screw 7 cavity bottom plate

The specific implementation mode is as follows:

a measuring device for low-temperature thermal resistance of an interface material comprises a measuring unit 1, a cold substrate 2, a cooling cold finger 3, a cold substrate temperature measuring element 4, a vacuum cavity 5, a connecting screw 6 and a cavity bottom plate 7. The measuring unit 1 comprises a radiation cover 1.1, a uniform heat block temperature measuring element 1.2, a heating resistance module 1.3, a fixing screw 1.4 and a uniform heat block 1.5. 4 measuring units 1 are distributed on the cold substrate 2 in a circumferential array manner by taking a circle with the radius of 35mm around the center of the cold substrate 2, and the low-temperature thermal resistance values of four groups of interface materials to be measured can be measured simultaneously in each measurement. The heating resistance module 1.3 is a ceramic heating sheet with the resistance value of 430 omega, the uniform heating block 1.5 is a cylindrical copper block with the radius of 15mm and the height of 5mm, and the interface material to be detected is made into a cylindrical sample with the diameter of 10 mm. One group is an indium sheet material with known thermal resistance, and the other three groups are graphene materials to be tested. The heat spreader 1.5 is screwed to the cold base plate 2 by M2 screws, and the fixing screws 1.4 are all set at 20cN M torque. The radiation cover 1.1 is a hollow cylindrical cover with the radius of 15mm and the height of 15mm and the wall thickness of 1mm, and is made of aluminum alloy material, and the outer surface of the hollow cylindrical cover is polished to reduce the surface emissivity. The cold substrate 2 is a cylindrical copper block with the radius of 60mm and the height of 15mm, the vacuum cavity 5 is made of kovar materials, and the inner wall of the vacuum cavity is polished to reduce the surface emissivity. The upper end of the cooling cold finger 3 is a cylinder with the radius of 60mm and the height of 10mm, and the lower part of the cooling cold finger is a hollow cylinder cavity with the radius of 33mm and the height of 72mm and the wall thickness of 2 mm. An indium sheet is arranged at the interface between the cooling cold finger 3 and the cold substrate 2 to reduce the interface thermal resistance. The bottom of the cavity bottom plate 7 is hermetically connected with the bottom end of the cooling cold finger 3 by electron beam welding.

During measurement, the interface material to be measured is clamped and installed between the uniform heating block 1.5 and the cold substrate 2, the vacuum cavity 5 is vacuumized to reduce the error influence of thermal convection on measurement, and the vacuum degree of the vacuum cavity 5 is kept at 10^-4And when the temperature is more than Pa, filling liquid nitrogen into the cooling cold finger 3, detecting the temperature of each temperature measuring element, and recording the temperature value of each temperature measuring diode when the temperature is stable. And then starting the heating resistance module 1.3, respectively applying heating powers of 0.4W, 0.8W, 1.2W, 1.6W and 2.0W, and recording the temperatures of three points when the temperature is stable under each heating power. The thermal resistance of each group of interface materials to be measured can be obtained by a steady state method, and the error in measurement can be reduced by a comparison method.

Claims

1. The utility model provides an interface material low temperature thermal resistance measuring device, includes measuring element (1), cold base plate (2), the cold finger of cooling (3), cold base plate temperature element (4), vacuum cavity (5), connecting screw (6), cavity bottom plate (7), its characterized in that:

the device is characterized in that two or more than two measuring units (1) are arranged on the upper surface of a cold substrate (2) in a circumferential array around the center of the cold substrate (2), fixing screws (1.4) penetrate through mounting through holes on a uniform heating block (1.5) and mounting through holes on the cold substrate (2) and are fixed in mounting threaded holes on the upper surface of a cooling cold finger (3), the measuring unit (1), the cold substrate (2) and the cooling cold finger (3) are connected together, the upper end face of the cooling cold finger (3) is fixed with the lower bottom face of the cold substrate (2) through a connecting screw (6), an interface material with good heat conduction performance is padded in the middle, the cold substrate temperature measuring element (4) is connected to the center of the cold substrate (2) through glue, the vacuum cavity (5) and the cavity bottom plate (6) are hermetically sealed through a rubber ring, and the bottom of the cavity bottom plate (7) is hermetically connected with the lower end of the cooling cold finger (3) through welding.

2. The device for measuring the low-temperature thermal resistance of the interface material as claimed in claim 1, wherein the measuring unit (1) comprises a radiation shield (1.1), a uniform heat block temperature measuring element (1.2), a heating resistance module (1.3), a fixing screw (1.4) and a uniform heat block (1.5). The radiation cover (1.1) with the polished outer surface or plated with the high-reflectivity coating is fixedly connected to the upper surface of the uniform heating block (1.5) through screws, and the size and the shape of the radiation cover (1.1) are matched with those of the uniform heating block (1.5). The heating resistance module (1.3) is connected to the center of the upper surface of the uniform heating block (1.5) through glue, and the uniform heating block temperature measuring element (1.2) is connected to the position, close to the heating resistance module (1.3), of the upper surface of the uniform heating block (1.5) through glue.

3. The device for measuring the low-temperature thermal resistance of the interface material according to claim 1, wherein the heat equalizing block (1.5) is circular or rectangular and has a size slightly larger than that of the interface material to be measured, the material is copper or sapphire with higher thermal conductivity at low temperature, the surface of the heat equalizing block (1.5) is plated with a high-reflectivity plating layer, and the heat equalizing block is provided with a fixing through hole for mounting a fixing screw (1.4).

4. The device for measuring low-temperature thermal resistance of interface materials as claimed in claim 1, wherein the material of the fixing screw (1.4) is engineering plastics or titanium alloy.

5. The device for measuring the low-temperature thermal resistance of the interface material as claimed in claim 1, wherein the cold substrate (2) is made of copper or sapphire, and is provided with fixing through holes for mounting fixing screws (1.4).